Abstract: The cited micro-organism was grown in a broth and harvested by centrifugation. The isolated microbes were dispersed in phosphate buffer of pH 7 and immobilized on a cellulose nitrate membrane by adsorption on to the pores, which was effected by filtration of a 0.5 mL portion of the dispersion through the membrane under reduced pressure. The prepared membrane was coupled to a dissolved O2 sensor by means of dialysis membrane kept in position with an O-ring. The sensor was used in a FIA system with phosphate buffer as the carrier stream (25 ml/h). Amperometric measurements were made at an applied potential of -0.6 V vs. Ag/AgCl. Calibration graphs were constructed with standard solutions of glucose/glutamic acid, and were linear up to 500 mg/l, corresponding to a BOD value of 370 ppm. The sensor, which is intended for application to effluents, exhibited good stability and a fast response time.